Synthesis & Characterization of Defects in Coatings and the Degradation of Polymeric Materials Public Deposited

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  • March 21, 2019
Creator
  • Ibrahim, Ahmed-Rufai
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • The field of macromolecular science has explored the ability of invoking high degrees of functionality to increase the applications in which materials may be utilized. In doing so, new characterization methodologies are necessary to better qualify and quantify their abilities and understand the dynamics behind their novel performance. This dissertation describes both of these areas, including the development of characterization methods for understudied biopolymers and emulsion-produced latexes, as well as the synthesis of novel polymers for achieving on-demand, segmented material depolymerization. In Chapter 2, a method was developed for investigating the role of different constituents of an acrylic coating in creating film defects. The defect of film sag was studied utilizing an electron paramagnetic resonance (EPR) spin probe. The probe allowed the curing process of a coating to be surveyed and how the binder of the coating responds to coalescence. By doing this for both horizontal and vertical orientations, the sag film defect was observed by a variation in polarity of the spin probe. This polarity was evident in the spectra of the probe and its shift in polarity was quantified over time. In Chapter 3, synthesis goals turn to creating copolymers possessing novel functionalities for use in self-healing materials and drug delivery methods. The described system utilizes self-immolative polymers (SIPs) to enable selective, on-demand depolymerization of materials. The triggers investigated were pH and heat, due to their relevance and abundance of use in biological applications. The synthesized polymers were able to be depolymerized to their monomeric parent molecules discriminately based on the stimulus which the copolymer was exposed to. Various characterization methods were utilized to ensure the kinetics of depolymerization, as well which material was depolymerized, could be controlled. To investigate the viability of this system in drug delivery, biologically relevant copolymers were synthesized to be incorporated in multi-dye possessing polymersomes capable of on-demand release of said dyes in response to orthogonal stimuli. Chapter 4 elucidates a method developed for the improvement of mucin characterization. Mucins are the macromolecules which make up mucus. The abundance of various mucins plagues patients with Cystic Fibrosis (CF) and Chronic Obstructive Pulmonary Disease (COPD). These patients utilize mucolytic agents, which are reducing agents that break down mucins. These agents, however, are largely ineffective and unsuccessful in their attempts to depolymerize mucins to-date. To aid mucolytic drug development and better understand the mechanism of mucin reduction, the described method aims to create more accurate molecular weight and size determination of mucins using Gel Permeation Chromatography (GPC) and Dynamic Light Scattering (DLS).
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Rights statement
  • In Copyright
Advisor
  • Brookhart, Maurice
  • Ashby, Valerie
  • Leibfarth, Frank
  • Cahoon, James
  • You, Wei
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2017
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